Pelvic tumour in child fought with Nucletron's new inverse treatment planning approach

Veenendaal 19 January 2001The Dutch specialist in radiotherapy, Nucletron B.V., announces first clinical use of a new inverse planning system. The application of this new radiation therapy procedure, which was developed by Nucletron B.V. in consultation with the Radiation Oncology Team at Children's Hospital, Los Angeles (CHLA), was performed last month. A five-year old girl underwent the new therapy for a pelvic germ cell tumour that has recurred three times, most recently in September 2000.

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The girl was the first person to receive treatment using the newly developed software. She underwent her first Intensity Modulated Radiation Therapy (IMRT) treatment, a method of planning and delivering conformal radiation using Nucletron's new PLATOcomplete Inverse Planning Software (PLATO ITP), on a linear accelerator with a 120-leaf collimator.

Nucletron's Plato Inverse Treatment Planning software provides tremendous clinical advantages over 3D forward treatment planning systems, according to Robert S. Lavey, M.D., M.P.H., Head Radiation Oncology Programme at CHLA, who added that Inverse Treatment Planning (ITP) forms a practical approach for both limiting radiation dose to sensitive body structures and for delivering accelerated, concomitant boost treatment in fractionation once daily.

"At Children's Hospital Los Angeles, we have compared treatment plans made with ITP to the best conformal plans we were able to design for our patients with brain, abdominal, and pelvic tumours. In each case, the ITP plan gave significantly less radiation dose to critical normal tissues while providing comparably homogeneous dose to the target. The software is easy to work with and responsive to our dose parameters. It equally directs the movements of our dynamic multi-leaf collimator flawlessly. I think that it requires no more time to plan or deliver ITP than conventional conformal treatments, with far more satisfying results", stated Dr. Lavey.

"We find that because of the easy user interface and fast optimisation routine, our time can be spent creating the very best treatment solution for each patient. From a physics standpoint, of critical importance is the ability of the Nucletron system to accurately calculate the dose from the numerous small segments applied with IMRT. The ionisation chamber measurements of absolute dose agree routinely with the ITP calculation to within 2 percent and isodose distributions as measured in film are in close agreement as well", explained Arthur J. Olch, Ph.D., Chief of Radiation Physics at CHLA.

The IMRT software technology was developed by Nucletron in co-operation with MRC Systems GmbH, based on research from the German Cancer Research Center, DKFZ, and in consultation with Drs. Robert Lavey, M.D. and Arthur Olch, Ph.D., and other leading cancer research centres. They set the radiation dose criteria for the tumour and the normal structures. The software interactively creates the optimal treatment plan for each patient, combining scores of radiation beam shapes, sizes and intensities. Their plan directs the movements of the 120 leaves of the collimator during the treatment to "sculpt" the radiation dose to match the tumour and avoid the normal structures.

The patient tumour has recurred in her pelvis three times despite high dose chemotherapy and repeated major surgeries, the first performed when she was four days old. She has had no evidence of metastatic disease during her five-year battle with this locally recurrent tumour. This is the first attempt at controlling her tumour with radiation therapy. The combination of IMRT and chemotherapy has been recommended by CHLA physicians to try to cure her disease, while minimising the short- and long-term effects of treatment.

With PLATOcomplete, Nucletron offers an advanced integrated solution for fast and intuitive planning of even the most complex radiation therapy treatment techniques. This includes accurate visualisation of patient set-up, with the ability to assign a genuine 3D margin around the tumour and the capability of inverse planning for Intensity Modulated Radiation Therapy (IMRT). This powerful blend of functionality combines the benefits of the Virtual Simulation System (VSS) and Inverse Treatment Planning (ITP) within PLATO.

The result is a work flow which is designed to speed through the normally complex steps of developing, optimising and evaluating a treatment plan for conventional 3D or Intensity Modulated Radiotherapy Therapy (IMRT). The optimisation algorithm employed in PLATO ITP provides results in minutes as well as an on-line update of dose distribution and DVH during the optimisation. Taking into account the characteristics of the treatment machine, the effects of the prescription can be evaluated immediately and approved prior to initiating the final Quality Assurance (QA) steps and export to the treatment machine.

PLATO ITP optimises plans for use with compensators as well as multi-leaf collimators (MLC), making IMRT possible with almost any linear accelerator, an important consideration when upgrades of treatment machines to include MLC capabilities or complete replacement are not immediate options. The resulting prescriptions can be exported to linear accelerators and Record and Verify systems, using either DICOM-RT, or the specific LANTIS format, which makes PLATO a universal choice suitable for supporting a varied range of treatment system configurations.

On PLATO systems with multiple workstations, the floating licenses and shared database enable an economical and integrated approach to all steps necessary for inverse treatment planning and required QA prior to treatment delivery. PLATO's shared architecture allows both conformal brachytherapy and external beam treatment plans to be combined and evaluated. Nucletron B.V. is a world-wide expert in radiotherapy systems and thoracic imaging equipment for radiology and mass chest screening and specialises in some of the most innovative products used for cancer treatment.

The company has 11 offices worldwide, including its corporate headquarter in The Netherlands and is a subsidiary of Delft Instruments, an international group of companies with 1100 employees and annual sales of over NLG 400 million. More information on Nucletron's PLATOcomplete system is available in the VMW September 2000 article Nucletron to treat prostate cancer with integrated solution for conformal brachytherapy.


Leslie Versweyveld

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